Powder cutting and scarfing of resistant metallic bodies



Patented Mar. 24, 1953 POWDER CUTTING AND SCARFING oF RESISTANT METALLIC BODIES:

Edward Meincke, Summit, N. J assignor, by

mesne assignments, to Union Carbide and Carhon, Corporation, a corporation of New York No Drawing. Application May 19, 1949, Serial No. 94,264

1 Claim- This invention relates to a novel process for thermochemically removing metal from a metal oralloy body which is substantially immune to the conventional procedure of impinging only a frame and an oxygen Jet against successive areas on said body; and more particularly relates to an improved metal-removing procedure for nonferrous metal bodies. In addition, the invention concerns a novel adjuvant powder composition useful in the novel process.

U. S. Patent No. 2,451,422, which issued October 12, 1948, to R. L. Wagner, discloses a novel process for thermochemically removing metal from immune metal bodies, both ferrous and nonferrous, by employing an adjuvant powder in conjunction with a preheating flame and a metalre'm-oving oxygen jet. Suitable adjuvant powders are iron (in the form of cast iron or steel), ferromanganese, manganese, and iron-tin alloys. Of these adjuvant powders, iron had proved to be the best for thermochemically removing metal from both ferrous and nonferrous metals and alloys prior to the present invention, having its greatest commercial application in the flame cutting and scarfing of high-chromium stainless steels. Iron powder is now being used for this purpose in quantities greater'than one million pounds per year.

Commercial application of the powder cutting and scarfing process to nonferrous metals has lagged because the specific adjuvant powders of the Wagner patent have not been sufliciently effective on thicknesses greater than 2 inches, because cutting with these powders has been relatively slow, and because surfaces of poor quality have been obtained. Thicknesses up to 2 inches could be machine oxygen cut, but above 2 inches manualoxygen cutting was necessary. In addi-, tion, it has frequently been necessary to bodily preheat nonferrous metal bodies to a high tem-- perature before oxygen cutting or scarring them.

The principal object of the present invention is to provide a novel improvement in the powder cutting and scarfing of immune metals and alloys whereby the commercial scope of the process is expanded to include both ferrous and ncnferrous resistant metal bodies. Other objects are to provide a novel improved process whereby nonferrous metals both more or less than 2 inches in thickness can be readily flame out; whereby machineflame cutting can be employed on nonferrous metals both more and less than 2 inches thick; whereby nonferrous metals can be readily flame scarred; whereby flame cut and flame scar-fed surfaces of good guality can b obtained 2 on nonrerrous metals; and whereby nonferrous metals can be flame out and flame scarfed with out bodily preheating them. Still another object is to provide a novel adjuvant powder composition useful in the novel process.

The present invention constitutes an important improvement in the process for thermochemically removing metal from immune metal or alloy bodies by continuously and concurrently impinging together against successive areas on such bodies an oxygen jet, a stream of powdered adjuvant material, and a heating flame. Specifically, the improvement comprises impinging the adjuvant material against the body as a powdered intimate mixture consisting essentially of iron and aluminum. As will be apparent from the detailed examples set forth below, the aluminum should constitute more than 10% but not more than of the mixture, by weight. Numerous tests have shown that when such a mixture of iron and aluminum is used in the process,.relatively great thicknesses of non-ferrous metals can be flame cut and flame scarfed without prebeating them, and at such a high rate that this process has become commercially important in competition with other procedures. Also this novel process produces cut and scar'fed surfaces of relatively good quality.

The novel process described briefly above can be carried out with any suitable powder cutting and scarring apparatus, such as that disclosed in Wagner Patent No. 2,451,422, or in my copending application Serial No. 547,062, filed July 28, 1944, now Patent No. 2,470,999 of May 24, 1949, of which the present application is a continuationin-part, or in Patents 2,444,899 and 2,444,900. Particularly good results are obtained in cutting when the powder is suspended in a gas such as air and blown through a separate tube having its outlet end positioned adjacent the tip of a conventional cutting or scarflng nozzle, so that the powder penetrates the ring of preheat flame and is heated to a high temperature before becoming associated with the oxygen jet, for example as shown in Figs. 5 and 7 of my aforementioned Patent No. 2,470,999; In scarfing, good results are obtained by suspending the powder in the oxygen jet before discharge from the nozzle, so that the stream of powder and the stream of oxygen actually issue in intimate association with one another as a powder-laden oxygen jet.

The following specific examples disclose in detail how the novel process can be carried out on immune metal and alloy bodies of various types.

Example I.Niclcel and nickel-base alloys A. A slab of nickel 6 inches thick and 30 inches wide was successfully flame cut using a mixture of iron and aluminum wherein the aluminum constituted 33% by weight of the mixture. Speeds up to 4.4 inches per minute were realized with powder flows as low as 15 ounces per minute, and cutting oxygen flows of 1100 cubic feet per hour. Using plain iron powder and conventional powder cutting equipment, it was not possible to cut deeper than 3 inches while maintaining a continuous movement of the torch.

B. A slab of nickel was also successfully flame scarfed to remove surface defects using a powder containing 20% of aluminum, but attempts to scarf the same slab with iron powder alone were not commercially satisfactory.

C. An alloy ingot 6 inches thick containing about 26% molybdenum and about 65% nickel was successfully machine flame cut using aluminum-iron powder compositions wherein various proportions of aluminum ranging between 10% and 65% by weight were tested. For example, cutting speeds of 3 inches per minute were obtained using 14 ounces per minute of a mixture containing 30% of aluminum powder, with a cutting oxygen flow of 810 cubic feet per hour. Previously the maximum thickness which could be flame cut using steel powder alone appeared to be 3% inches, and thicknesses greater than 2 inches required crude and slow manual operation of the torch.

D. Ingots of the same alloy as in Example I above were also successfully flame scarfed to remove surface defects by using a powder containing 20% by weight of aluminum. All previous attempts at flame scarfing this alloy had been commercially unsatisfactory in competition with other procedures.

E. A slab 6 inches thick and 30 inches wide of an alloy containin about 68% nickel and about 29% copper was flame out under the same operating conditions and with identical results as in Example I A.

Example II.-C'opper and copper-base alloys A. A section of copper pig 9 inches thick was readily cut at a speed of about 2 inches per minute, using an iron-aluminum powder containing 25% of aluminum flowing at a rate between 16 and 24 ounces per minute, and an oxygen flow of 1100 cubic feet per hour. Previous work with standard powder cutting equipment and iron powder showed that the maximum thickness of copper that could be severed was 1 inch.

B. Several pieces of naval brass 4 inches and 6 inches thick were successfully flame cut with powders wherein the aluminum ranged between 10% and 65% by weight, but the best results were obtained with between 15% and 60% of aluminum powder. Relatively smooth cuts were obtained using powder flows as low as 5 ounces per minute and as high as 16 ounces per minute. The cutting speed on pieces 6 inches thick was about 3 inches per minute, and on pieces 4 inches thick was about 3.5 inches per minute using a cutting oxygen flow of 1100 cubic feet per hour.

In specific examples, a bar of brass 4 inches thick was cut at a speed of 3 inches per minute when using 16 ounces per minute of a powder mixture composed 85 of iron powder and 15% of atomized aluminum powder; and when using about 8 ounces per minute of a powder mixture composed 40% of iron powder and 60% of atom- '4 ized aluminum powder. The maximum depth of cut that could be obtained with iron powder unmixed with aluminum powder was 2 inches at a speed of 3 inches per minute. At the same speed, no cut could be obtained when using a powder mixture composed 30 of iron powder and 70% of aluminum powder.

C. Several large manganese-bronze ship propellers were flame cut to charging-box size by removing two of the three blades. In removing each blade a cut 66 inches long was made adjacent to the hub and through a section having a maximum thickness of about 6 inches at a speed of about 2 /2 inches per minute using about 16 ounces per minute of an aluminum-iron powder mixture containing about 25% of aluminum and a cutting oxygen flow of 1100 cubic feet per hour. The powder process was several times faster than the standard method of partially melting through the blades with a carbon arc and then completing the severing operation by dropping a weight from an overhead crane.

D. Using iron powder the maximum cutting speed on sheets of 70/30 copper-nickel sheet inch and inch thick was approximately 12 inches per minute. When a powder composition containing 15% of aluminum and of iron powder by weight was used at a rate of 4 ounces per minute, the cutting speed was increased to 25 and 38 inches per minute on the inch and /8 inch thick material, respectively, usin cubic feet per hour of oxygen.

Emample III.Aluminum A section of aluminum '7 inches thick was successfully cut at a rate of 4 inches per minute using an aluminum-iron powder mixture containing 25% of aluminum by weight, and an oxygen flow of 1100 cubic feet per hour. The maximum thickness of aluminum which had been cut previously by standard powder cutting practice using iron powder was 1 inch.

Example I V.-T1mgsten steel While the novel aluminum-iron powder mixture is particularly advantageous for flame cutting and scarfing non-ferrous metals, it has also been found to be superior to other powders for flame cutting resistant steels containing tungsten. For example, a mixture of iron and aluminum wherein the aluminum constituted 30% of the mixture by weight was used for successfully flame scarfing Society of Automotive Engineers grade 7290 and 7250 tungsten steels at high speeds. When using mixtures of ferromanganese and iron powders scarfing was slow and the cuts produced were very shallow.

A mixture of aluminum and iron powders also is effective for oxygen cutting and scarfing of other resistant metallic materials such as cast iron, and stainless steels containing large amounts of chromium. Also, the novel powder composition of the invention can be used for rapidly starting a flame cutting or scarfing reaction on plain carbon steels which do not require the application of adjuvant powder after the start has been obtained. As described in detail in my Patent No. 2,470,999, a mixture of 20% aluminum and 80% iron has been used for such a starting procedure.

As a general rule a powder blend containing a relatively low percentage of aluminum requires a relatively high powder flow and produces a cut of superior quality. A lower powder flow can be used with a blend containing higher percentages of aluminum, but the surface produced is rougher.

The powder mixture should be of such a fineness that 100% thereof will pass through a 100- mesh screen having .0058 inch openings. It is also desirable for at least 70% of the powder mixture to pass through a 200-mesh screen having .0029 inch openings, and for at least 40% to pass through a 325-mesh screen having .0017 inch openings. Furthermore, it is advantageous to use granular or atomized aluminum powders in the mixture because of their superior flow characteristics and because a homogeneous mixture can be maintained with such powders. Flake aluminum powder tends to fly off into the atmosphere after leaving the nozzle, and also tends to separate out of the mixture in a powder dispenser.

The improved results obtained on nonferrous metals with the powder composition of the invention are believed to be due tothe fact that the powdered aluminum has a greater affinity for oxygen than the iron powder and has a faster rate of combustion so that it initiates the cutting reaction along the top edge of the out. Some of the less active and slower burning iron powder starts to burn as soon as it impinges on the preheat flame, but the greater part of it is not ignited until it penetrates deep into the material and then completes the cutting reaction in the lower part of the cut.

What is claimed is:

Process for the thermochemical removal of metal of the group consisting of copper, nickel, brass, bronze and nickel base alloys containing molybdenum from a body of such metal which comprises continuously impinging against the initial portion of a metal yielding zone of said body a preheating flame; concurrently continuously impinging against the initial portion of said metal yielding zone heated by said preheat flame a metal removing oxygen jet; concurrently continuously introducing to said oxygen jet a stream of gas borne adjuvant powder consisting essentially of iron and granular aluminum powders intimately mixed together, said aluminum consisting of more than 10% and not more than of said mixture by weight, the lower percentages yielding smoother surfaces and the higher percentages yielding lower powder flow, said powder being heated by said preheating flame to the oxygen kindling temperature of its constituents, and said heated powder and oxygen stream contacting with the metal yielding surface along the concurrent extent thereof; and mechanically progressing said preheating flame, heated powder and oxygen stream and metal yielding zone along the metal body; the faster burning aluminum granules initiating the reaction at the beginning of the metal yielding zone, and the slower burning iron powder combining and continuing the reaction to the end of the metal yielding zone, and thereby extending the reaction along the concurrent extent of the heated powder and oxygen stream and metal yielding zone for a total distance of at least two inches, and enabling the mechanical progression thereof to proceed at a rate of from 2 to more than 4 inches per minute.

EDWARD MEINCKE.

REFERENCES CITED The following references are of record in the file of this patent: 

1. PROCESS FOR THE THERMOCHEMICAL REMOVEL OF METAL OF THE GROUP CONSISTING OF COPPER, NICKEL, BASS, BRONZE AND NICKEL BASE ALLOYS CONTAINING MOLYBDENUM FROM A BODY OF SUCH METAL WHICH COMPRISES CONTINUOUSLY IMPINGING AGAINST THE INITIAL PORTION OF A METAL YIELDING ZONE OF SAID BODY A PREHEATING FLAME; CONCURRENTLY CONTINUOUSLY IMPINGING AGAINST THE INITIAL PORTION OF SAID METAL YIELDING ZONE HEATED BY SAID PREHEAT FLAME A METAL REMOVING OXYGEN JET; CONCURRENTLY CONTINUOUSLY INTRODUCING TO SAID OXYGEN JET A STREAM OF GAS BORNE ADJUVANT POWDER CONSISTING ESSENTIALLY OF IRON AND GRANULAR ALUMINUM POWDERS INTIMATELY MIXED TOGETHER, SAID ALUMINUM CONSISTING OF MORE THAN 10% AND NOT MORE THAN 65% OF SAID MIXTURE BY WEIGHT, THE LOWER PERCENTAGES YIELDING SMOOTHER SURFACES AND THE HIGHER PERCENTAGES YIELDING LOWER POWDER FLOW, SAID POWDER BEING HEATED BY SAID PREHEATING FLAME TO THE OXYGEN KINDLING TEMPERATURE OF ITS CONSTITUENTS, AND SAID HEATED POWDER AND OXYGEN STREAM CONTACTING WITH THE METAL YIELDING SURFACE ALONG THE CONCURRENT EXTENT THEREOF; AND MECHANICALLY PROGRESSING SAID PREHEATING FLAME, HEATED POWDER AND OXYGEN STREAM AND METAL YIELDING ZONE ALONG THE METAL BODY; THE FASTER BURNING ALUMINUM GRANULES INITIATING THE REACTION AT THE BEGINNING OF THE METAL YIELDING ZONE, AND THE SLOWER BURNING IRON POWDER COMBINING ANC CONTINUING THE REACTION TO THE END OF THE METAL YIELDING ZONE, AND THEREBY EXTENDING THE REACTION ALONG THE CONCURRENT EXTENT OF THE HEATED POWDER AND OXYGEN STREAM AND METAL YIELDING ZONE FOR A TOTAL DISTANCE OF AT LEAST TWO INCHES, AND ENABLING THE MECHANICAL PROGRESSION THEREOF TO PROCEED AT A RATE OF FROM 2 TO MORE THAN 4 INCHES PER MINUTE. 